The present invention relates to a brake and, more particularly, to a brake for a caster which wedges between the wheel hub and fork of the caster to arrest the motion of the caster wheel.
Casters equipped with brakes are used in a variety of applications. For example, they are commonly used on computer carts, hospital beds and food service carts, as well as heavier duty applications such as on U-boat carts used to stock shelves in a super market.
Prior art brakes for casters are generally designed to impede the rotational motion of the caster by locking onto the periphery of the caster wheel, i.e. the rolling surface of the wheel. A typical prior art caster brake will include a generally L shaped brake. One leg of the L will be pivotally attached to the axle bolt of the caster while the other leg will grip the periphery of the wheel when pressure is applied to the brake.
However, the pressure of the prior art brakes on the periphery of the wheel has a tendency to deform the shape of the wheel and/or the brake. Additionally, if the gripping portion of the brake includes edges which are not sufficiently rounded, the brake may bite into the periphery of the wheel causing further deformation to the wheel. In an attempt to prevent deformation, prior art brakes are often heat treated, which further adds to the cost and complexity of the caster. Moreover, due to their complexity, prior art brakes are not easily retrofit to existing casters in the field.
A variety of caster brakes, having shapes other than that of an L, can also be found in the prior art. One such example of a prior art caster is disclosed in U.S. Pat. No. 2,096,229 issued to Dudley (hereinafter Dudley). Dudley relates to caster brakes wherein the object of the invention is to provide a brake for a caster in which the brake shoe is pivoted on an axis eccentric to the axis of the caster wheel by a cam member. The pivots are eccentric to the axis of the caster wheel so that in turning the brake shoe in a counter-clockwise direction on the pivots the brake shoe is rotated into engagement with the periphery of the caster wheel.
However, the locking surface in Dudley is on the periphery of the wheel. Additionally, a cam member is required to be actuated to lock the brake, adding to the cost and complexity of the caster. Furthermore, the brake cannot be shipped as a spare part and retrofit to casters in the field.
Other examples of a prior art caster brakes are disclosed in U.S. Pat. Nos. 2,512,941, 3,902,576, 4,385,414, and 5,829,096. In each case, the brake locks the caster by frictionally gripping the peripheral surface of the wheel. Additionally, the brakes are not designed to be retrofit in the field.
Accordingly, there is a need for an improved brake for a caster which does not lock on the periphery of the caster wheel, is simple and inexpensive to manufacture and can be retrofit in the field to existing casters.
The present invention offers advantages and alternatives over the prior art by providing a caster brake which wedges between the fork and wheel hub of a caster to impede the rotational motion of the caster wheel. The brake is free from contact with the periphery of the caster wheel; therefore avoiding any deformation of the wheel or the brake as braking pressure is applied. The brake is also simple in construction and inexpensive to manufactured. The brake can also be shipped as a spare part to be retrofit to existing casters in the field.
These and other advantages are accomplished in an exemplary embodiment of the invention by providing a brake for a caster having a caster wheel with a wheel hub axially mounted to a fork. The brake includes a leg adapted to pivotally engage the fork of the caster. When the brake is mounted to the caster, the leg wedges between the fork and the wheel hub to frictionally arrest the motion of the caster wheel.
In an alternative embodiment of the invention, when the leg of the brake wedges between the fork and the hub, the brake is free from contact with the periphery of the caster wheel.
In another alternative embodiment of the invention the brake has a generally U shape. The brake includes a pair of legs extending outwardly from a closed base end. The pair of legs has distal end portions which are bent at an angle to project outwardly from a center line of the brake. The distal end portions are adapted to pivotally engage a pair of inside walls of the fork of the caster. When the brake is mounted to the caster, the legs wedge between the inside walls of the fork and the wheel hub to frictionally arrest the motion of the caster wheel.